After graduation Smith served as assistant surveyor on many projects, including under Captain Emory on the survey of the northeastern boundary between the United States and Canada.

Smith moved to Washington Territory in 1855 where he supervised the building of various lighthouses along the Pacific coast and Strait of Juan de Fuca.

Smith was appointed chief registrar of the United States General Land Office in Seattle in 1860 and was an aide-de-camp to Governor Isaac Stevens.

During the American Civil War, when the Union Army invaded his home state, Smith had to flee north to British Columbia because of his well-known Southern sympathies.

He then worked in British Columbia in the employ of the Dominion Government where he conducted a survey of the Fraser River from Soda Creek to Lytton to examine the feasibility of steamship travel.

From 1876 to 1878 he served on the Board of Railroad Commissioners for the State of California, and was appointed chief engineer of the Sacramento River Drainage Commission.

Smith then returned to Washington in the employ of the Northern Pacific Railroad and was put in charge of surveys through the Cascade Range to find the most practical route across to Tacoma.

He designed and supervised the building of the 24-mile (39 km) pipeline from the newly surveyed Bull Run Reservoir to Portland, from which the city still gets its drinking water.

His life was colored strongly by his sense of duty, his sterling and unapproachable integrity…" Smith is buried in a very plain grave in section three of River View Cemetery, in the Teal family plot.